Modelling and Performance Analysis of MgB2 and Hybrid Magnetic Shields

Superconductors are strategic materials for the fabrication of magnetic shields, and within this class, MgB2 has been proven to be a very promising option. However, a successful approach to produce devices with high shielding ability also requires the availability of suitable simulation tools guiding the optimization process. In this paper, we report on a 3D numerical model based on a vector potential (A)-formulation, exploited to investigate the properties of superconducting (SC) shielding structures with cylindrical symmetry and an aspect ratio of height to diameter approaching one. To this aim, we first explored the viability of this model by solving a benchmark problem and comparing the computation outputs with those obtained with the most used approach based on the H-formulation. This comparison evidenced the full agreement of the computation outcomes as well as the much better performance of the model based on the A-formulation in terms of computation time. Relying on this result, the latter model was exploited to predict the shielding properties of open and single capped MgB2 tubes with and without the superimposition of a ferromagnetic (FM) shield. This investigation highlighted that the addition of the FM shell is very efficient in increasing the shielding factors of the SC screen when the applied magnetic field is tilted with respect to the shield axis. This effect is already significant at low tilt angles and allows compensating the strong decrease in the shielding ability that affects the short tubular SC screens when the external field is applied out of their axis.     

Multitarget microangiopathy in a young healthy man with COVID-19 disease: A case report

A 41-year-old man presented to the emergency department complaining of decrease of vision in his left eye. Initial examination was consistent with retrobulbar optic neuritis, and an intravenous drip of methylprednisolone was started. On the third day, the fundus examination revealed the appearance of multiple Purtscher-like cotton-wool spots in the posterior pole and nasally to the optic disc, slight retinal whitening around the fovea, and cherry-red spot. The patient reported flu-like symptoms, and he tested positive at PCR (polymerase chain reaction) test for 2019-nCoV (2019 novel coronavirus) infection. Assuming possible 2019-nCoV-related vascular damage, we prescribed low-molecular-weight heparin. The lesions were regressing at follow-up, and we registered a complete visual recovery.     

Relapse in medulloblastoma: what can be done after abandoning high-dose chemotherapy? A mono-institutional experience

Purpose

We retrospectively report strategies used for medulloblastoma patients progressing after craniospinal irradiation where we aimed for: symptom control, a satisfactory quality of life, accrual in phase 1–2 trials, when available, and the first two conditions could no longer be satisfied by already experienced second-line strategies.

Methods

Surgery was used in cases of doubtful relapse or when only one site was affected. Radiotherapy was given whenever possible, especially to relieve symptoms. The main chemotherapy regimens were oral temozolomide/etoposide, intravenous (iv.) cisplatin/etoposide, iv. gemcitabine/oxaliplatin, an oral sonic hedgehog pathway inhibitor and oral melphalan.

Results

Between 1998 and 2011, we treated 18 patients relapsed after median 20 months. Nine had relapsed locally, four had dissemination, three single metastases, and two had one synchronous local and metastatic recurrence. Responses to chemotherapy were seen in 32 % of cases. The median hospital stay for treatments/complications was 19 days. The 1- and 3-year progression-free survival (PFS) rates were 28?±?10 % and 0 %, respectively, for OS, they were 44?±?12 % and 22?±?10 % but no patient was cured. The median PFS after a first relapse was 7 months (range 1–29); the median OS was 7 months (range 4–44). No patients died due to treatment toxicity. Late recurrence (more than 1–2 years after diagnosis) and involvement of single sites were favorable prognostic factors.

Conclusions

Without succeeding in patients cure, we ensured them further treatment with short hospital stay thus affording low personal and social costs. The chances of cure may emerge from tailored therapies according to genetic stratification.     

Cardiovascular responses elicited by electrical stimulation of the amygdala central nucleus in the rabbit

Recent behavioral and anatomical evidence suggests the involvement of the amygdala central nucleus projection to medullary cardioregulatory nuclei in the expression of conditioned bradycardia during aversive Pavlovian conditioning in the rabbit^6,7,11,15. The present study sought to determine the extent to which electrical stimulation of the central nucleus produces bradycardia in the rabbit, and the extent to which any bradycardia elicited varies with stimulation at sites within as opposed to adjacent to the medial component of the central nucleus, the component from which the projection to cardioregulatory nuclei originates. Over 900 sites in 30 rabbits anesthetized with α-chloralose were explored. Monopolar stimulation (30–100 Hz; 0.5 ms pulse duration; 5.0 s train duration; 100–500 μA) at sites within the central nucleus produced bradycardia and depressor responses. Maximum bradycardia was produced from sites within the anterior, medial component of the nucleus. This respose usually began within one second of stimulus onset, reached peak magnitude within two seconds of stimulus onset and in many instances was followed by a slight tachycardia following stimulus termination. The accompanying depressor responses occurred at longer latencies than the bradycardia responses. The responses persisted following artificial ventilation and immobilization by Flaxedil and were attenuated by i.v. injections of atropine methylnitrate. While bradycardia and depressor responses were elicited from sites immediately dorsal, ventral and lateral to the medial central nucleus, these responses were of markedly less magnitude than those elicited from the medial component. The results are consistent with previous evidence which suggests a contribution for the central nucleus in the expression of cardiovascular responding during aversive Pavlovian conditioning in the rabbit.     

Satisfaction,quality of life and therapy adherence assessment in real life patients transitioning from vitamin K antagonists to direct oral anticoagulants

Journal of Thrombosis and Thrombolysis - Anticoagulant therapy has undergone a significant change since direct oral anticoagulants (DOACs) introduction. Their obvious advantages including the fixed...     

Morphometric studies of the aged hippocampus: I. Volumetric analysis in behaviorally characterized rats

The present investigation examined the structural integrity of the aged hippocampus by using computer-aided morphometry to quantify the volume of principal hippocampal circuits in young, mature adult, and aged Long-Evans rats. A key feature of the experimental design was that the status of hippocampal-dependent learning and memory was documented prior to histologic evaluation. The following regions, which were visualized by using Timm staining, were included in the analysis: 1) outer portions of the dentate gyrus molecular layer (OML) innervated by the lateral entorhinal cortex, 2) middle portions of the molecular layer (MML) that receive input from the medial entorhinal cortex, 3) the commissural/associational zone (IML) immediately adjacent to the granule cell layer, and 4) the hilus and mossy fiber projection to the CA3 pyramidal cell field (MF). To identify morphometric changes that emerge during the same segment of the life span as age-related learning impairment, analysis of the volumetric results focused on comparisons between the mature adult group and the aged group. Among the individual regions that were analyzed, age-related decreases in total volume were restricted to the MML. This effect, however, occurred against a background of other, subtle changes that, together, reflected substantial reorganization in the normal balance of hippocampal circuitry. Age-related decreases in the proportion of the molecular layer (ML) that comprises the MML were accompanied by a corresponding increase in relative IML volume. The ratio between the volumes of the MML and the MF also displayed significant age-related decline. Overall, aging affected septal levels of the hippocampus disproportionately, and, with the exception of MML/MF volume ratio, the temporal hippocampus was spared. Finally, the status of spatial learning among the aged animals correlated selectively with decreases in the MML/ML and MML/MF ratios. These results demonstrate that the effects of aging are regionally selective and circuit specific, and they suggest that connectional reorganization may contribute to age-related decline in the computational functions of the hippocampus. J. Comp. Neurol. 403:459–470, 1999. © 1999 Wiley-Liss, Inc.     

Lesions of basolateral amygdala impair extinction of CS motivational value,but not of explicit conditioned responses,in Pavlovian appetitive second-order conditioning

The basolateral amygdala (BLA) is important for the modification of the motivational significance of events through associative learning. In previous work, we found that BLA was critical for the acquisition of conditioned reinforcement value to a visual conditioned stimulus (CS) paired with food. Unlike normal rats, rats with neurotoxic lesions of the BLA failed to acquire Pavlovian second-order conditioning to an auditory stimulus paired with the first-order visual CS in the absence of food. In this experiment, we examined the role of BLA in the extinction of the previously acquired conditioned reinforcement value of a Pavlovian CS. Rats received first-order visual CS-food pairings prior to either BLA- or sham-lesions. Subsequent CS-alone extinction training reduced the ability of the visual CS to reinforce second-order conditioning of an auditory stimulus in the sham-lesioned rats, but not in the BLA-lesioned rats. Despite this persistence of the conditioned reinforcement value of the visual first-order CS in the BLA-lesioned rats, no effects of the lesions were observed on extinction of the explicit behavioural conditioned responses elicited by that CS.     

Nucleotide-mediated calcium signaling in rat cortical astrocytes: Role of P2X and P2Y receptors

ATP is the dominant messenger for astrocyte-to-astrocyte calcium-mediated communication. Definition of the exact ATP/P2 receptors in astrocytes and of their coupling to intracellular calcium ([Ca(2+)](i)) has important implications for brain physiology and pathology. We show that, with the only exception of the P2X(6) receptor, primary rat cortical astrocytes express all cloned ligand-gated P2X (i.e., P2X(1-5) and P2X(7)) and G-protein-coupled P2Y receptors (i.e., P2Y(1), P2Y(2), P2Y(4), P2Y(6), and P2Y(12)). These cells also express the P2Y-like UDP-glucose receptor, which has been recently recognized as the P2Y(14) receptor. Single-cell image analysis showed that only some of these receptors are coupled to [Ca(2+)](i). While ATP induced rapid and transient [Ca(2+)](i) increases (counteracted by the P2 antagonists suramin, pyridoxal-phosphate-6-azophenyl-2'-4'-disulfonic acid and oxidized ATP), the P2X(1)/P2X(3) agonist alphabetameATP produced no changes. Conversely, the P2X(7) agonist BzATP markedly increased [Ca(2+)](i); the presence and function of the P2X(7) receptor was also confirmed by the formation of the P2X(7) pore. ADP and 2meSADP also produced [Ca(2+)](i) increases antagonized by the P2Y(1) antagonist MRS2179. Some cells also responded to UTP but not to UDP. Significant responses to sugar-nucleotides were also detected, which represents the first functional response reported for the putative P2Y(14) receptor in a native system. Based on agonist preference of known P2 receptors, we conclude that, in rat astrocytes, ATP-induced calcium rises are at least mediated by P2X(7) and P2Y(1) receptors; additional receptors (i.e., P2X(2), P2X(4), P2X(5), P2Y(2), P2Y(4), and P2Y(14)) may also contribute.